1. Field of the Invention
The present disclosure generally relates to a winding structure of a stator, and an electric machinery using the stator and, more particularly, to the winding of copper coils around such a stator that consists of 8 magnetic poles that interact with an also 8-pole rotor to generate electricity.
2. Description of the Related Art
Stators are essential components for constructing electric machinery that includes motor and generator. Among various kinds of electric machinery, designs of stators with 8 magnetic poles, henceforth referred to as 8-pole stators, are indeed not new as they can be found in literature and are available commercially.
In a conventional electric machinery, however, each magnetic pole of the stator has the same number of turns of winding. Therefore, when the electric machinery is in action, every magnetic pole generates electricity of the same magnitude as induced by the magnetic field of the rotor. As a result, the magnetic poles of the rotor, also termed armature, tend to bear a large magnetic impedance when the poles of the rotor are in transit between two adjacent magnetic poles of the stator. Such typically large magnetic impedance is one of the main factors that lead to energy loss to heating and poor efficiency of the electric machinery.
As a consequence of such heating loss, the temperature of each magnetic pole of the stator would increase after the electric machinery operates for certain duration of time. Because of the even number of windings of the stator and the rotor, the heating loss are also evenly distributed to each pole, hence causing largely equal rise of temperature. The eventual high temperature of the magnetic poles of the stator always compromises the operational efficiency of the rotor in various general ways. Even worse, the temperature of the rotor will also increase as the temperature of the stator rises, either due to radiation or by convection. Consequently, unless properly dissipated, the heating problem would cause various detrimental effects to a conventional electric machinery, including lifetime, energy efficiency, and environmental issues, among others.
It has been known that when the overall temperature of the electric machinery increases, the magnetic loss due to the iron core, including the magnetic hysteresis loss and eddy current loss, and resistive loss of the copper windings of the electric machinery would also increase, leading to increased power losses, both the active and the reactive components, of the electric machinery and, thus, significantly lowering the efficiency of an electric machinery. In all, the rotor needs to bear a higher magnetic impedance during rotation and thus if the heat dissipation issues cannot be resolved, any attempt to further improve the efficiency of electric generation or conversion of electric power would prove difficult, if possible at all.